First Aid Kit is two sisters, ages 18 and 21, from Sweden. But their music sounds like a slice of Americana: acoustic guitar, autoharp and lots of vocal harmony.

Klara and Johanna Soderberg wrote the songs for their new album, The Lion's Roar, while on their last tour. Many started with ideas, short riffs, recorded on a cellphone.

"Klara had done some different parts for different songs. And I just listened to it and I realized that we can just put all these ones together, and it's a finished song," Johanna explains.

First Aid Kit is known for sweet melodies paired with lyrics that are often dark — like the song "Blue," which includes the couplet, "And the only man you've ever loved that you thought was gonna marry you / Died in a car accident when he was only 22." Klara says she's been writing songs like this since she was 14.

"Writing the song is sort of like dealing with the fear of becoming these women ourselves," Klara says.

The song "King of the World" is a collaboration with Bright Eyes, whom Klara credits as the reason she started writing songs at age 12. She says she never imagined she'd team up with one of her heroes.

And now, let's move onto one of NPR Music's most anticipated albums of 2012. "The Lions Roar" by the band First Aid Kit is out tomorrow.

(SOUNDBITE OF SONG, "EMMYLOU")

FIRST AID KIT: (Singing) Oh, the bitter winds are coming in and I'm already missing the summer...

INSKEEP: First Aid Kit is two sisters, ages 18 and 21, from Sweden, making music that sounds like a slice of Americana.

KLARA SODERBERG: I am Klara. I am the younger sister. I play guitar and I sing in our band, First Aid Kit.

JOHANNA SODERBERG: And I'm Joanna. And I play keyboard and autoharp, and sing, too.

INSKEEP: Klara and Johanna Soderberg wrote the songs for this album while on their last tour. Many, like what you're hearing now, started with ideas, short riffs recorded on a cell phone.

J. SODERBERG: Klara had done some different parts like for different songs. And I just like listened to it. And I realized, well, we can just put all these ones together and it's a finished song.

INSKEEP: And the result was the song "Emmylou."

(SOUNDBITE OF SONG, "EMMYLOU")

FIRST AID KIT: (Singing) I'll be your Emmylou and I'll be your June. And you'll be my Gram and my Johnny, too. No, I'm not asking much of you. Just sing, little darling, sing with me.

INSKEEP: First Aid Kit is known for harmonies like what you were just hearing, and sweet melodies paired with lyrics that are often dark.

(SOUNDBITE OF SONG, "BLUE")

FIRST AID KIT: (Singing) And the only man you ever loved, that you thought was going to marry you, died in a car accident when he was only 22.

INSKEEP: Klara says she's been writing songs like this since she was 14.

K. SODERBERG: Writing the song is sort of like a way of us dealing with our fear of sort of like becoming these women ourselves.

INSKEEP: Women who have lost their voices.

(SOUNDBITE OF SONG, "KING OF THE WORLD")

FIRST AID KIT: (Singing) And once you asked me, what was my biggest fear, that things would always remain so unclear. That one day I'd wake up all alone with a big family and emptiness deep in my bones.

INSKEEP: That song is called "King of the World," one of the new ones from Klara and Johanna Soderberg of First Aid Kit. Their latest album, "The Lion's Roar," is out tomorrow but you can hear it right now at our website, nprmusic.org.